Sounds like someone's bought a car without checking it over properly first. These cars are very high tech and, dare I say, perhaps somewhat over engineered, which of course means more things can go wrong. And with a bit of bad luck they will all go wrong at the same time. I'm on my second Jag at the moment and I dare not think off the enormous amount of money spend on keeping the first one on the road. It will suffice to say it cost more than twice as much to keep it running than it was to buy it. Unfortunately I have been stung by the car bug years ago so I was forced to buy another one. This time I did make sure it's got a full service history and I checked the car over in daylight and with a friend. Still it's cost me £600 already to fix the exhaust manifold and the wheel bearings, replace the lambda probe and 2 tyres, as well as all kinds of little niggling problems.
But every time I take her out for a drive I feel lucky still and I if I have some time off I try and take the long route home, just so I can enjoy the richness of driving a Jaguar.
I agree high tech, but disagree with the over engineering. Jaguar as well as every other British car has a lack of engineering and quality control. I've owned Mercedes, Jaguar and a few Mg's. Hands down to the Mercedes for excellent build quality, engineering and durability. The Jaguar is like a dumb blonde.
From what you are explaining, so many problems could be caused by a vehicle that has been flooded with water.
I've had plenty of luck with my XJ6. I take very good care of it and I do routine maintenance myself. i.e. air filter replacement, oil change, fuel filter change, chassis lubrication, etc.
If you buy a Haynes manual and learn to do it yourself, it becomes fun and practical.
As long as the car is maintained properly, it will treat you with endless reliability. If you don't feel like doing it yourself or paying somebody to service it, then don't bother owning one. Go drive a Mercedes or BMW, but don't expect to have the same soul in the car as a Jaguar.
I'm 18 years old, and if I can do it, there is no excuse why anybody else can't.